2,000 holes per second - the result of electron beam perforation. © Pro-beam

As many workpieces are joined from individual parts, the process enables the use of more cost-effective materials. An intelligent design can also eliminate the need for expensive machining or erosion work. In general, electron beam welding offers high speed and is considered very reliable. For example, the electron beam welds a one meter long seam with a depth of 100 mm in less than a minute. After the joining process, the components are ready for installation and do not have to be laboriously reworked. These are the main reasons why companies with high productivity benefit most from joining technology. However, companies that want to join materials that are considered difficult to weld, such as mixed compounds, aluminum, copper, titanium, duplex steel or nickel-based materials, can also take advantage of the technology. The welding process also works with rough surfaces and can take place at any stage of the production chain - even at the very end, as it does not interfere with other processes such as mechanical finishing, surface finishing or the assembly of components. Electron beam welding is also suitable for components with sensitive inner workings, such as sensors. Low heat transfer to the surrounding material or to the underlying electronics is extremely important in the manufacture of pressure sensors, for example, in order to maintain their full functionality. However, the Electron Beam is not only suitable for welding. It is also ideal for drilling several thousand holes per second. Particularly small hole diameters, high hole counts and deep holes can be easily achieved with the process.

How does electron beam welding work?

In electron beam welding, a heated cathode initially generates a cloud of free electrons. As a rule, electrons are firmly bound to atoms, but they can be released from the lattice structure of the solid when energy is applied. The electrons are then accelerated to the anode by an electric field. Electromagnetic lenses form a focused beam from the free electrons. They reach a speed of between one and two thirds of the speed of light. As the electron beam can be deflected magnetically, it can be precisely controlled and is capable of performing even complex welding tasks.

The entire welding process takes place in a vacuum. When the electrons hit the material, they emit heat with pinpoint accuracy, while the surrounding material remains largely cold. At energy densities of over 107 W/cm2 , the molten substance in the center finally^evaporates . This creates a capillary of vapor surrounded by liquid material.

Vacuum enables the processing of refractory metals such as titanium, zirconium or niobium and is even more cost-effective than the use of shielding gases. In general, working under vacuum results in clean workpieces and a better quality weld seam - compared to conventional processes. Intelligent airlock concepts prevent the generation of vacuum at the expense of production time.

Chamber systems and airlock shuttle systems

The K6000 welding chamber is located in the Pro-beam plant and is the largest civilian welding system in the world. © Pro-Beam

Electron beam welding systems are available in two different versions: Chamber systems and lock shuttle systems. Pro-beam, one of the leading companies in the field of electron beam welding, has the world's largest welding chamber in the civil sector. The K 6000 has a volume of 700^m3, operates via an internal generator and has been specially developed for welding very large and heavy components. The system can join components measuring up to 7 m x 7 m x 14 m and weighing up to 100 tons with an evacuation time of less than 35 minutes.

Dr. Thorsten Löwer, Director of Development and Systems Engineering, pro-beam Group. © Pro-beam

Small components that only require a short preparation time can be processed in systems that build up and release the vacuum in an airlock. In this way, no time is lost during production for evacuating the chamber and it can be used continuously. In Pro-beam systems, the main chamber is preceded by an airlock, which prevents the high vacuum in the working chamber from being impaired and allows three work processes to run in parallel: loading and unloading of the workpieces on the pre-bed, evacuation and ventilation in the airlock and electron beam treatment in the working chamber. Systems based on such a system can also be integrated into a fully automated production process and optimized for Industry 4.0 environments.

Dr. Thorsten Löwer, Chief Development and Systems Engineering Officer, Pro-beam Group / am